KDP paperback cover size and spine width by page count

The formulas

KDP’s paperback cover is one continuous file with back cover, spine and front cover side by side, plus bleed on the outside edges:

• Cover width = 0.125 in + trim width + spine width + trim width + 0.125 in
• Cover height = 0.125 in + trim height + 0.125 in

Spine width is page count multiplied by the paper’s thickness: 0.002252 in for white, 0.0025 in for cream, 0.00235 in for groundwood and 0.002347 in for premium color.

Worked example

A 300-page 6 x 9 in paperback on white paper:

• Spine: 300 × 0.002252 in = 0.6756 in
• Width: 0.125 + 6 + 0.6756 + 6 + 0.125 = 12.9256 in
• Height: 0.125 + 9 + 0.125 = 9.25 in

On cream paper the spine becomes 300 × 0.0025 = 0.75 in and the cover 13 in wide. Paper choice changes the cover, so set ink and paper before designing.

Spine text

KDP only prints spine text on books with at least 79 pages; Cover Creator needs 80. A shorter book with spine text is rejected. Keep at least 0.0625 in (1.6 mm) between spine text and each spine edge, because binding can shift.

Use the cover calculator

KDP’s cover calculator and template generator takes ink, paper, trim size and page count and produces a template showing full cover, safe areas, spine and barcode area. It is the safest source when KDP’s pages disagree: the Create a Paperback Cover page lists standard color at 0.002252 in per page while the Paperback Submission Guidelines give one color figure of 0.002347 in.

Common mistakes

• Designing for the wrong page count. Final page count is rounded up to an even number.
• Keeping text closer than 0.125 in to the trim lines.
• Leaving important art where KDP places its barcode if you do not supply one.

Amazon changes these rules; the linked KDP help pages are the authority.